气流干燥的进展

本文介绍气流干燥的基本机理和最简单的气流干器形式·这种设备的使用范围为加料器和干燥器的研究开发打下了基础,从加料作为整干燥流程的一部分出发,介绍简单、完善的加料器·干燥器研究的范围:从“热文丘里”型沸腾干燥器到环流干燥器·本文还介绍一些专门研究的内容,包括低熔点物料的干燥、多级干燥、闭路循环干燥、除去和回收溶剂·并期望通过进一步研究,提高气流干燥器的适应性和干燥效率,使它在大规模工业生产应用中继续普及矿·     

逆流干燥硬脂酸盐

硬脂酸金属盐是熔点较低的物质,一般生产过程中常用烘箱或气流干燥器干燥成品,但在气流干燥过程中,不能采用较高的热空气进口温度,因此热效率不能提高。根据硬脂酸盐湿物料比较容易粘附成团及干燥温度不能过高的特点,研制了以粉碎干燥机及旋风干燥器逆流联接的干燥流程(见右图)。本流程中的主要设备有: 1.粉碎干燥机φ600×1700,内设旋轴及刮片,可同时作粉碎及干燥用。2.星型阀,用直流电机带动,可调速。3.旋风干燥器φ800×φ530×2100,是上大、下小     

尾气循环气流干燥工艺研究及干燥器的选型

通过实际设计实例分析了循环尾气气流干燥工艺及干燥器的选择关系。气流干燥器的操作压力影响着尾气出口的露点温度;随着载气温度的增加,载气的载湿能力增加;气流干燥器出口的湿度、燃气耗量由物料的干燥特性和循环风量决定。普通干燥器与脉冲气流干燥相比,尽管其需要的高度相对较高,停留时间短,但其压降低、加工制造简单,安装操作简易。     

直管气流干燥器的设计计算

本文以内蒙古化工厂干燥某产品的工艺参数和物料特性为依据,选择直管气流干燥器完成干燥任务。本文设计计算了干燥管的尺寸,选择了旋风分离器及风机等辅助设备。设计结果为：干燥管管径150mm,干燥管管长18m。     

气流旋转干燥器

1 旋风气流干燥器 旋风气流干燥器的干燥室结构以圆筒形居多,但也有锥形结构,锥形干燥室可使物料颗粒旋转速度由小到大,能达到强化干燥的目的. 旋风气流干燥器由内筒和外筒组成.外筒呈上大下小的锥形,物料从上部切线进入干燥器后,随热风向下部进行旋转运动,在干燥室内物料被干燥.到达底部后受气流夹带,粉体从内筒向上运动,经出料口排出.旋风气流干燥器的优点是使物料及热空气在干燥器内形成的转向降低了设备的高度,延长了物料在干燥器内的停留时间.     

影响片状湿含物热风干燥效果因素的实验分析

通过在实验室洞道式干燥器里对胡萝卜切片的干燥实验,比较了热风温度、干燥风速、物料片的厚度与形状对胡萝卜干燥过程影响,综合实验数据拟合胡萝卜片热风干燥曲线、干燥速率曲线分析,得到胡萝卜干燥效率较佳的干燥条件是热风温度为70℃,干燥风速为110.3m3/h(或0.946m/s),切片厚度为2mm。随着温度和风速的增加,干燥速率增加,恒速段干燥时间变短。实验分析结果对工业生产中干燥工序如何选用设备、设定操作要求具有指导意义。     

热敏性物料的低成本干燥法

<正> 美国WERNER＆PFLEIDERER公司生产的螺旋式干燥器是一种节能型干燥器。对于热敏性物料的干燥,其操作成本比普通干燥器低50％,目前螺旋式干燥器已成功地应用于粉状和直径至3mm的颗状物料的干燥处理,具体包括各种工程树脂,粉状杀虫剂,有机物和聚烯烃类树脂等。为适应处理     

气流干燥器史话

<正> 气流干燥器是广泛应用的干燥设备之一。所谓气流干燥器,如图1所示,是把湿润状态的泥状、块状、粉粒体状等物料,采用适当的加料方式,如螺旋加料器2,将请物料入干燥管1中,和加热器3加热的热空气流接触混合,湿物料在气流输送过程中被干燥,蒸发的水蒸汽进入热气流中,热空气温度下降,干燥后的产品由旋风分离器5下部排出,废气由旋风分离器上部用风机6     

组合干燥系统在氰尿酸生产中的应用

本文通过对氰尿酸干燥前后物料性质的分析，提出了应用于氰尿酸干燥的气流一盘式连续干燥系统，介绍了这种组合设备的结构、工作原理，阐述了其工艺流程及工作特点，分析了这种组合形式的优势及应用领域，并通过与另外一种干燥器——厢式干燥器在工作效率、能耗、操作的连续性及干燥后产品的质量等方面的比较，表明了在氰尿酸干燥作业中这种组合干燥器是干燥设备的最佳选择。     

强化气流干燥机的设计

介绍了强化气流干燥机的设计方法.强化气流干燥机是在直管气流干燥器的基础上发展起来的,用于解决各种农药滤饼的干燥问题,对高黏度膏状物料的干燥有很好的效果.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.